This suggests new thoughts on temp of earth when life
began.

The Evolution of the Primitive Atmosphere
James F. Kasting
Department of Geosciences, Penn State University,
University Park, PA 16802
kasting@essc.psu.edu
Environmental conditions on the early Earth are
important for both the origin and the early evolution
of life. Two variables are of particular
significance: 1) the atmospheric redox state,
and 2) the mean
surface temperature. Most recent models of Earth